Automatic reversing mechanism



May 31, 196() R. v. NlcoLosl ET AL 2,938,396

AUTOMATIC REVERSING MECHANISM Filed may 2e, 1959 2 sheets-sheet 1 [QRlg\ @N f KW .,/V I I z:

ATTO R N EY May 31, 1960 R. v. NlcoLosl ETAI- 2,938,396

- AUTOMATIC REvERsING MECHANISM Filed May 26, 1959 2 Sheets-Sheet 2 T1CVZ..

'fIII xNvENToRS Pas-Rr V, /V/co/.o s/ Aux Kor-e7? ATTORN EY UnitedStates Patent O AUTOMATIC` .REVERSIN G MECHANISM Robert V. Nicolosi,Valley Stream, and Max Kotler, Seaford, `N.Y., assignors,- by mesneassignments, to Fulton'W. Sandler, West Orange, NJ.

Filed May '26, 1959, Ser. No. 815,858

6 Claims. (Cl. 74'322) This invention relates to gear train meansadapted for converting unidirectional rotation of drive means about anaxis into alternating or bidirectional rotation of driven means about anaxis, and in particular, the invention is especially suitable forimparting alternating motion to apparatus, such as a multi-turnpotentiometer, for the purpose of regulating its operation between itsresistive limits.

It .is`the principal object of the invention disclosed herein to providegear train means capable of converting an input constituted by aunidirectional rotation into an output constitutedr by a bidirectionalor alternating rotation and to effect such conversion automatically withprecision, accuracy and reliability. The input mechanis-m may beconstituted by a drive shaft continuously turned in a preselected singledirection about its axis. The output .mechanism may be constituted' by adriven shaft, which in accordance with the practice of this inventionwill turn about its axis, first in one direction and then the other, inresponse to continuous turning of the drive shaft in one direction. As afurther advantage of the invention,` the improved gear train mechanismis adaptable for divers uses in any one of a number of different fieldsof application for imparting and regulating rotation of any load devicerequiring oscillating motion.

It is a further object of the invention to provide a reversing geartrain mechanism for converting a unidirectional rotational inputautomatically to va bidirectional or alternating rotational outputconstituted by structure capable of precision operation and compactnessin size, offering reliability, efficiency and economy in operation anduse and also being relatively economical and simple in manufacture.

lt is a further object of the invention to provide .means for regulatingand' varying the resistance of a rheostat requiring alternating rotationof a turnable component about an axis, which means is capable ofconverting a continuous input of unidirectional turning into an outputof alternate rotation whereby the resistance of the rheostat may bereciprocated between its two limits.

It is a further object of the invention to provide means for convertingunidirectional input rotation of drive means about an axis. intoalternating rotation of driven means about an axis constituted by a geartrain including a pair of spaced metering gears adapted for individualrotation in opposite directions in response to turning of the drivemeans, and including turnable metering means adapted for alternatetravel from one to the other of two positions wherein the metering meanstemporarily keys with one of said gears when in one position andthentemporarily keys with the other of said gears for the second of itspositions such that the metering means turns with the gear keyedtherewith. The metering means is also keyed. to the driven means toimpart a controlled rotation thereto. The devicey also includes ametering operator for regulating alternate travel of the metering meanswherein the metering means is. retained keyed with one gear fordetermining the direction of turning of the driven means in onedirection and then is released for keying with the vother gear forimparting reversed turning to the driven means.

Further objects and advantages will become apparent from the followingdescription of the invention taken in conjunction with the gures, inwhich:

Fig. l is a cutaway longitudinal plan view and in section andillustrates an automatic reversing gear train mechanism in accordancewith the practice of the invention;

Fig. 2 is an enlarged fragmentary view looking down upon the gearmechanism of Fig. l with parts rthereof cutaway to show certain of thecomponents of the mechanism; and

Fig. 3 is a plan end view of the apparatus taken along line 3-3 of Fig.1 and .shows certain of the components thereof in section and otherspartially cutaway to illustrate the operational relationship betweenmany of the components constituting the mechanism` Reference is now madeto the figures for an illustration of a reversing gear mechanism inaccordance with the practice of the claimed inventions. In theillustrated embodiment, the invention is adapted to control the travelof a lwiper 10 of a potentiometer 11. The gear mechanism is contained ina hollow and substantially cylindrical shaped housing 12 and' includes amain drive shaft 13. Shaft 13 has a front end 13a projecting from theinterior of housing 12. The front end 13a of the shaft provides meansfor turning or otherwise manipulating shaft 13 either manually or bysome control unit not shown herein, ln accordance with the invention,drive shaft 13 .is adapted to rotate about its axis only in onedirection, either clockwise or counterclockwise, for causingpotentiometer wiper 10 to travel between two limit positions. For thepurpose of analyzing the invention herein, `it will be assumed thatdrive shaft 13 at all times turns clockwise in the direction of arrow A.

Drive shaft 13 is journalled byspaced forward and rear bushings 14a, bsupported, respectively, in the front -wall of housing 12 and in adisc-shaped mountingplate 15. Mounting plate 15 Vis supported upright ina rear region of housing 12 by bolt screws 19. A pair of axially spaceddriving gears 16, -17 are mounted on drive shaft 13 to' turn therewith.Although gears 16, 17 may be designed as separate units individuallykeyed to shaft 13, vin the illustrated embodiment, .gears 16, 17 areintegral components of a single unit, lwhich unit is keyed to shaft 13by a set screw 18. Hence, gears 16, 17 turn in the direction depicted byarrow kA. A driven shaft 20 is supported in housing 12 adjacent and inparallel relationship in respect to shaft 13. Shaft 20 is adapted toturn in either direction about its 4longitudinal axis. The ends ofdriven shaft 20 are journalled by forward and rear bushings 21a, bsupported, respectively, in the front wall of housing 12 and in mountingplate 15. A driven or metering gear 23 is mounted to rotate freely onthe forward end of shaft 20. Gear 23 is continuously in toothedengagement with an idler gear 24. Idler 24 is `continuously in toothedengagement with forward driving gear 16. Idler 24 is supported by ashaft 25 to turn in the direction of arrow B, Fig. 3. Shaft 25 isjournalled by suitable means between the .front wall of housing 12 andmounting `plate 15. By reason of the foregoing arrangement, gear 23 isadaptedl for continuous turning in the clockwise direction of arrow A(Fig. 3) in response to turning of driving shaft 13.

A second driven or metering gear Z6 is mounted in front of mountingplate 15. Gear 26 is also adapted `to rotate freely on driven shaft 20.Gear 26 is continuously inv toothed engagement with and driven directlyby rear driving gear 17, whereby gear 26 is adapted to turn continuouslyin the direction of arrow C (Fig. 3). Consequently, by means of theforegoing arrangements,

28a, b are held fast to screw 27 by suitable means, ,Y

whereby screw 27 and pins 28a, b are adapted to undergo alternate axialtravel along shaft and turning about the axis of shaft 20 as a singleunit. Pins 28a, b are longer than screw V27, whereby the left and rightside ends of the pins protrude laxially from the forward and A rearfaces of screw 27. Y The circular metering disc 29 is keyed or otherwiseheld fast to shaft 20. Disc 29 registers in an -annular recess in shaft20 whereby a flange 31 of shaft 20 is peened to clamp disc 29 so thatthe latter turns continuously with shaft 20. Disc 29 has "spacedclearance openings at 32, which openings are aligned to permit theforward ends of pins 28a, b to extend slidably therethrough. Pins 28a, bare of such `length to insure engagement with disc 29 continuously evenwhen screw 27 is at its extreme right position. By means of theforegoing arrangement, shaft 20, pins 28a, b and disc 29 are keyed torevolve about the axis of shaft 20 as a single unit.

Each of the driven gears 23, 26 has a pair of spaced openings 33, 34suitably aligned to receive and slidably t over the individual ends ofpins 28a, b. When screw l`27 and thus pins 28a, b are shifted to theleft, the forward ends of the pins are adapted to fit into and engageopenings 33 in gear 23. When screw 27 and thus pins 28a, b are shiftedto the right, the rearward ends of pins 28a, b are adapted to tit intoand engage holes 34 in gear 26. The axial length of pins 28a, b areselected so that they alternately engage one and then the other of the`metering gears 23, 26 to turn therewith. In the illustrated position ofmetering screw 27 (Fig. 1), the right side ends of pins 28a, b are keyedto gear 26. When pins 28a, b are in this position, their left side endsdo not reach into holes 33 of gear 23, although pins 28a, b are longenough to engage disc 29. Consequently, it will be understood that pins28a, b are adapted to be rotatably keyed to either one or the other ofdriven gears 23, 25, but not to both gears simultaneously, wherebyrotation of the particular gear temporarily keyed to the pins isimparted to shaft 20 via metering disc 29.

The outer surface of metering screw 27 is threaded at'35. A meteringnut'36 is provided with an internal thread and is operatively mountedfor axial travel along lscrew27. Metering nut 36 is held againstrotation by a spring biased system which includes a metering plate 37provided with -a central opening fitted over metering nut 36. Meteringplate 37 is held fast to nut 36 by a flange 38 of nut 36, which ange ispeened against plate 37. In a front plan view, Fig. 3, metering plate 37is substantially' oval in shape and has diametrically opposed transverseends provided with inwardly turned recesses 39a, b. The spring biasedsystem also includes a pair of spaced diametrically opposed meteringposts 40, 41. Posts 40, 41 are held in fixed parallel relationshipbetween the front wall of housing 12 and mounting plate 15. The rightside post 41.is shown fully in Fig. 2, `whereas the left side -post isbroken away in the figure to permit a detail view of other parts of themechanivsm. In all respects, the-two posts are identical in structureand in their operational coaction with respect to metering plate 37,hence only one post is shown for the purpose of description.

' 1I-"he posts are provided with forward and rear surface 'action ofsprings 49.

4 portions 42, 43 of a rst outer diameter separated by an intermediateportion 44 of slightly larger outer diameter. Forward and rear abutmentwashers 45, 46 are mounted in xed positions at the end portions of eachpost 40, 41, for example by being held fast in correlated posts. Eachpost has a pair of axially spaced stop shoulders 44a, b formed by theend faces of the intermediate portion 44 of the posts. Each post isprovided with forward and rear metering sleeves 47, 48. Metering sleeves47, 48 are operatively mounted for slidable axial travelnalternatelyalong forward and rear surface portions 42, 43, respectively. Each postis also provided with forward and rear metering springs 49, 50, whereineach metering spring is individually operatively mounted to act againstan individual metering sleeve. Metering springs 49, 50 are held incompression between anges 51a, b of correlated sleeves 47, 48 andabutments 45, 46.

During operation of the reversing mechanism, nut 36 is adapted toundergo alternate shifting from one to another of two end positionsalong screw 27 during the interval of operation when screw 27 is keyedto a respective one of gears 23, 26. During axial shifting of nut 36,metering plate 37 is carried therewith. When nut 36 approaches its endposition along screw 27, for example the rear or right end position,plate recesses 39a, b slidably advance over the forward ends of sleeves48 whereby plate 37 is brought into pressing contact against sleeveanges Slb to carry sleeves 48 rearwardly along post portions 43 againstsprings 50. The. springs are designed to stop rearward movement of theassemblage shortly after sleeves 48 are engaged. This halts vtravel ofnut 36, whereby screw 27 is suddenly shifted by instantaneous actionunder the force of the loaded springs 50 to the left to disengage fromgear 26 and keyed in with gear 23. The foregoing shifting actionreverses rotation of screw 27, whereby nut 36 will start travel alongscrew 27 towards its forward end position and as it does, plate recesses39a, b will soon slide off rear sleeves 48 and slidably traversemid-section 44 and then slidably overlap the forward pair of sleeves 47.Accordingly, plate recesses 39a, b are dimensioned to permit freeslidi'ng of plate 37 onto and off from the engaged portions of meteringsleeves 47, 48 and over the intermediate post portions 44. In theillustrated embodiment, the outer diameters of sleeves 47, 48 overlappedby plate recesses 39a, b and the outer diameter of portions 44, are thesame size.

Operation of the reversing mechanism will now be considered wherein,drive shaft 13 is assumed to be continuously rotated by means not shownand in the direction of arrow A to cause continuous rotation of meteringgears 23, 26 in the directionsY of arrows A and C, rc- Spectively, asdepicted in the figures. For the position of metering screw 27, as shownin Fig. l, it will be assumed for the moment that metering nut 36 is atits forward end position along screw 27 `as depicted in dashed outlineinFig. 1. For the foregoing assumed position of nut 36, forward sleeves 47are held by nlate 37 at an intermediate position along post portions 42against the force of springs 49. For the foregoing assumed position ofthe mechanism components, screw 27 is axially stationary at rest againstgear 26, whereby screw 27 is turning in the proper direction to forcenut 36 to travel therealong to its rear or right end position. Anyavailable conventional means may be employed for determining maximumaxial translation of screw 27 along shaft 20 during operation of themechanism. In the enclosed cmbodiment, screw 27 comes to rest at itsrespective end positions when the correlated end faces thereof bearagainst the confronting faces of disc 29 and gear 26. vAs nut 36commences rearward axial travel along screw 27, sleeves 47 follow plate37 by reason of the expanding The stored force provided by springs 48also overcomes the inertia of the system to facilitate initial axialmovement of nut 36 along screw v27. Continued rotation of screw 27causes nut 36 to rreach mid-section 44 wherein vplate 37 slides olf theen- .gaged portions of forward sleeves 47, which sleeves come to restagainst stops 44a. Plate 37 slidably advances rearwardly overVmid-section 44 .and then slidably overlaps rearward sleeves 48 as plate37 picks up flanges ,5,1b to carry sleeves 48 therewith. Sleeves 48 wereat rest -against stops 44b under the action of springs '5.0 until pickedup by the moving plate 37.

As noted hereinbefore, springs 5 0 are designed to furnish an opposingload which soon vhalts the` moving assemblage soon after plate 37 picksup and advances sleeves 48. By reason of such action, nut 36 can nolonger advance rearwardly along screw 27. Since the illustratedstructure prevents rotation of nut 36 about the axis of screw 27,continued rotation of screw 27 in the vdirection of arrow C causes asudden axial shifting of `screw 27 and its assemblage to ythe .leftalong shaft 20 under the force of springs 50. Such action withdraws pins28a, b from holes 34 of ,gear 26 and then causes the left side ends ofsaid pins to key into holes 33 of gear 23. The foregoing shift of theassemblage is relatively instantaneous once it commences. If holes 33 ofturning gear-23 are not aligned to receive the approachingA pins, thepins will slide along the confronting face of gear 23 until holes 33 arealigned for the pins to key therein under the force of springs 50. It isdesirable to bevel the opposite ends of the pins, Ias depicted in thefigures, to facilitate keying of same into .the gear holes.

Once screw 27 is keyed to turn with gear 23, the direction of turning isnow proper to force axial travel of nut 36 to the left or its forwardend position. The assemblage vis designed so that at the. start of suchnut movement, sleeves 48 have not yet come to rest against stops 44b torelieve the assemblage of the pushing force still being furnished bysprings 50. This is desirable for two reasons. It supplies sufiicientspring loading to assist initial movement of nut 36 to the left toovercome inertia of the system; and secondly, it drives pins 28a, baxially deeper into gear ,holes 33, which pins will ultimately locktherein as screw 27 rotates with gear 23. It will be understood that asimilar locking arrangement lexisted when the right ends of pins 28a, bwere keyed with gear 26. Hence, springs 50 are characterized to applysufficient loading force to effect theV previously described shifting ofscrew 27 and its yassemblage from a temporarily locked engagement withvmetering gear 26 and to assure keying of the pins into gear 23. Theforegoing characteristics described to springs 50 also apply to springs49 for similar purposes to obtain a similar disengagement with respectto gear 23 "and shifting of screw 27 and its assemblage to the right ata subsequent portion of the cycle of operation.

It is thus seen that springs 49, 50 in a sense operate as thrust.storage devices to impart axial travel of nut 36 along screw 27. In thepreferred embodiment, the arrangement is such that axial travel of nut36, as it alternates between its end positions, is stopped short ofactual contact with the confronting surfaces of disc 29 and gear 26 bysprings 49, 50 to prevent binding of the mechanism. Forexample, Fig. 1shows nut 36 at its right end position spaced adjacent but notcontacting gear 26.

Returning now to operation of the mechanism, screw A2.7 will come torest against disc 29. With screw 27 turning in the direction of arrowA', nut 36 travels to its forward position yand as it does, plate 37slides olf rear sleeves 48 as the forward ends thereof are halted bystops 44b. Plate 37 traverses post mid-portions 44 and then slidablyoverlaps forward sleeves 47 resting against stops 44a to pick up sleeveflanges 51a. Further forward Iadvancement of the assemblage is soonbrought to a halt by springs 49 with nut 36 axially at rest yat itsforward position adjacent'- but not contacting disc 29. Continuedrotation of screw 27 in the direction of arrow A' causes. the loadedsprings 49 to suddenly shift screw A6 27 and its assemblage ininstantaneous action to the right to :effect disengagement from gear 23and keying into gear 26, wherein the previous sequence of events is nowrepeated.

It is desirable that the foregoing `described spring load means impartuniform resilient loading to the diametricallyopposite sides of plate37, whereby plate 37, and thus nut, 36, is maintained relativelyorthogonal to the of. shaft 20 when engaged by the springs. This isachieved by individual axial adjustments to posts 40, 4.1. The frontends of the posts slidably fit into respective bushings 52 carried inthe front wall of housing 12. The back ends of the posts are threaded at53 and, accordingly, threadedly held by respective bushings S4 carriedby mounting plate 15. By threadedly adjusting each post with respect tobushings S4, the individual posts may be moved forwardly or rearwardlyto a xed desired position. In addition, the foregoing arrangement willcompensate for individual loading variations imparted` by the springs.

It will be understood that the number of turns experienced by shaft 20for each axial sweep of nut 36 from `one to the other of its endpositions along screw 27 .may be decreased or increased 4by axiallyrepositioning the limit stops for nut 36 for a given metering screw.This may be achieved by various means, including changing the axiallocation of flanges 51a, b along sleeves 47, 48. For example, if flanges51b are located closer to the front ends of sleeves 48, nut 36 isbrought to a halt further away from the rear end face of screw 27 whichwill decrease the number of rotations experienced by shaft 20 forturning in each of its directions.

The illustrated gear train mechanism is adaptable Afor use in any one ofa number of different elds 4of application for regulating -any loaddevice requiring oscillating motion. The mechanism is particularlysuitable for use wherein continuous unidirectional motion is desired foroperating a device requiring alternating bidirectional motion. Forexample, in the disclosed embodiment the output of shaft 20 is designedto impart continuously alternating bidirectional motion to the rotatablecomponent of potentiometer 11.

Potentiometer 11 has a turnable barrel 55, the shaft 56 of which isadapted for bidirectional turning. One end of barrel shaft; 56 isjournalled in a rear wall of a potentiometer casing 57 and the forwardend of shaft S6 is journalled by a race 58. Turnable movement isimparted to barrel shaft 56 by a gear 59 keyed thereto, which gear 59 isin meshed engagement with an output gear 60 supported at the end ofdriven shaft 20 and on the rear side of mounting plate 15. Gear 60 iscarried by a hub 61 held to the end of shaft 20 by a bolt screw 62.Potentiometer 11 is enclosed by casing 57 which is attached to the openrear end of housing 12 by a clamp ring 63.

Barrel has a pair of similar spiral grooves 64, 65. A resistance wire 66is wound in groove 64. The other groove serves as a guide for a wipertrolley 67, which trolley has a pin 68 slidably keyed' with groove 65.Trolley 67 is mounted for slidable movement on a stationary rail 69supported parallel to the axis of barrel 55. As rheostat barrel rotatesalternately in opposite directions, correlated reciprocating movement isimparted to wiper 10 as it slidably contacts resistance wire 66, wherebythe resistance of potentiometer 11 is reciprocated between its limits.In the preferred embodiment of potentiometer 11,

it is desirable to synchronize the movements of nut 36 along screw 27and wiper 10 along rail 69, such that both alternate to their respectivelimit positions at -the same time and thus travel in unison. This may beachieved by arranging screw 27 and barrel 55 to turnin accordance withlsimilar pitch ratios. As noted hereinbefore, the number of wiperrevolutions for turning in each direction may be decreased by decreasingthe separation between the metering nut limit stops. The rate of Vtweenits limit values.

Yof moving parts thereof.

`travel of wiper may differ for movement in one direc- `tion withrespect to the other direction by selective adjustment of gear ratiosbetween gears 16, 23 and 17, 2.6. For example, gears 16, 23 may beprovided with a 1:1 ratio and gears 17, 26 may be provided with a 2:1ratio Vwhich will result in wiper 10 travelling twice as fast in onedirection as the other. As a further advantage of the invention, thegear mechanism may be made extremely light in weight and compact in sizeand is thus yespecially adaptable for aircraft usage or other usage`requiring compact light-weight structures. In particular, the size ofthe gear mechanism in comparison to potentiometer 11 may be relativelysmaller in size. Furthermore, the gear mechanisms eliminates the need'of limit stops as normallyl required for potentiometers havingrevolvable components for alternating its resistance be- The limit stopsfor potentiometer 11 are those operatively co-acting against nut 36.Moreover, durability and long-life operation of the gear mechanism maybe extended appreciably by suitable hardening In one working embodimentof the invention for the purpose of regulating potentiometer operation,the gear mechanism was driven to impart a 250 r.p.m. to driven shaft 20and springs 49, 50 were :characterized by a 3 oz. thrust. Lightersprings may be used for manual operation, whereas stronger springs arerequired Awhen operating driven shaft 20 at higher speeds.

It is intended that all matter contained in the above description orshown in the accompanying drawings shall be interpreted as illustrativeand not in a limiting sense.

What is claimed is:

l. A reversing mechanism for converting continuous rotation of drivemeans in a preselected direction about an axis into alternate rotationof second means about an axis comprising, drive means adapted forturning in a preselected direction about an axis, driven means adaptedfor alternate turning about an axis, a pair of turning -meansindividually rotatable in opposite directions with respect to each otherin response to turning of said drive means, turnable metering meansadapted for axial travel alternately from one to another of twopositions, said metering means being keyed individually to each of saidturning means in response to being at one or the other of its twopositions, rotation imparted to said metering vmeans being controlled bythe direction of turning of the particular one of said turning meanskeyed therewith,

said metering means also being operatively associated 'with said drivenmeans to impart rotation thereto, a metering operator 'adapted foralternate axial displacement from one to another of two positions alongsaid metering means, means temporarily retaining said operatoralternately at correlated ones of its positions on said metering means,said metering means being ad'apted to travel axially from one to theother of its positions iny response to said operator being retained inan individual one lof its positions to alternate rotation of said drivenmeans, said retaining means being adapted to release said operator fordisplacement from one to another of its two positions by reason ofcorrelated turning of said metering means in response to being keyedwith a particular one of said turning means during that period ofoperation wherein said metering means is axially stationary at acorrelated one of its positions, and means continuously holding saidoperator against rotation, said metering means having a threaded outersurface, and said operator having a threaded interior surface and beingoperatively mounted for travel along said threaded outer surface.

2. Apparatus as defined in claim 1 wherein, said drive ,and driven meansbeing individual rotatable shafts, said lturning means being freelyrotatable on said driven shaft, ,and means coupled to said drive shaftfor individually `rotating said turning means in opposite directionswith respect to each other.

K 3, A reversing mechanism for converting continuous rotation of drivemeans in a preselected direction about an axis into alternate rotationof second means about an axis comprising, drive means adapted forturning in a preselected direction about an axis, driven means adaptedfor alternate turning about an axis, a pair of turning meansindividually rotatable in opposite directions with respect to each otherin response to turning of said drive means, turnable metering meansadapted for axial travel alternately from one to another of twopositions, said metering means being keyed individually to each of saidturning means in response to being at one or the other of its twopositions, rotation imparted to said metering means being controlled bythe direction of turning of the particular one of said turning meanskeyed therewith, said metering means also being operatively associatedwith said driven means to impart rotation thereto, a metering operatoradapted for alternate axial displacement from one to another of twopositions along said metering means, and means temporarily retainingsaid opf crator alternately at correlated ones of its positions on saidtravel axially from one to the other of its positions in response tosaid operator being retained in an individual one of its positions toalternate rotation of said driven means, said retaining means beingadapted to release said operator for displacement from one to another ofits two positions by reason of correlated turning of said metering meansin response to being keyed with a particular one of said turning meansduring that period of operation wherein said metering means is axiallystationary at a correlated one of its positions, said metering meansincluding, axially overlapping members having opposed ends for keyinginto individual ones of said turning means.

4. Apparatus as defined in claim l wherein said operator retaining meansand said continuous holding means comprising, a pair of longitudinalposts with individual ones of said posts on diametrically opposite sidesof an axis, a metering plate fixed to said operator and havingdiametrically spaced openings overlapping individual ones of said postsfor preventing turning of said operator, abutment means at the endportions of said posts, a pair of axially spaced stop shoulders at theintermediate portions of said posts, forward and rear metering sleevesfor each post, individual ones of said sleeves being operatively mountedfor slidable travel on either side of said stop shoulders of said posts,individual metering springs operatively associated with each meteringsleeve, said springs being held in compression by correlated ones ofsaid abutments and metering sleeves, the openings of said mounting platebeing dimensioned to slide onto and off from said metering sleeves andover the intermediate portions of said posts between the stop shouldersthereof during axial travel of said operator, one spring of each postdefining a forward pair and being loaded' in compression by reason ofsaid mounting plate slidably overlapping and engaging the forward onesof said sleeves and thus carrying same against said springs until themoving assemblage is stopped by the loaded springs, one spring of eachpost dening a rearward pair and being loaded in compression by reason ofsaid mounting plate slidably overlapping and engaging the rearward onesof said sleeves and thus carrying same against said springs until themoving assemblage is stopped by the loaded springs, initial axialdisplacement of said operator from one to the other of its positionsbeing aided by the loaded pair of correlated springs while the axiallystationary metering screw is turning in a direction to effect travel ofsaid operator therealong and continued displacement of said operatoralong said metering means releases the loaded springs whereby theoperatively associated metering sleeves are stopped by correlated onesof said stop shoulders to allow said metering plate to slide olf suchsleeves and traverse the intermediate post portions and then slidablyoverlap the other pair of metering sleeves to load the springsoperatively 9 associated therewith until halted by the loaded springs,continued turning of said metering means now results in axial shiftingof same in a direction from which said operator originated to cause saidmetering means to disengage from a correlated one of said turning meansand key into the other one of said turning means whereby rotation ofsaid metering means is reversed which results in return travel of saidoperator.

5. A reversing mechanism for converting continuous rotation of drivemeans in a preselected direction about an axis into alternate rotationof second means about an axis comprising, drive means adapted forturning in a preselected direction about an axis, driven means adaptedfor alternate turning about an axis, a pair of turning meansindividually rotatable in opposite directions with respect to each otherin response to turning of said drive means, turnable metering meansadapted for axial travel alternately from one to another of twopositions, said metering means being keyed individually to each of saidturning means in response to being at one or the other of its twopositions, rotation imparted to said metering means being controlled bythe direction of turning of the particular one of said turning meanskeyed therewith, said metering means also being operatively associatedwith said driven means to impart rotation thereto, a metering operatoradapted for alternate axial displacement from one to another of twopositions along said metering means, and means temporarily retainingsaid operator alternately at correlated ones of its positions on saidmetering means, said metering means being ad'apted to travel axiallyfrom one to the other of its positions in response to said operatorbeing retained in an individual one of its positions to alternaterotation of said driven means, said retaining means being adapted torelease said operator for displacement from one to another of its twopositions by reason of correlated turning of said metering means inrespnse to being keyed with a particular one of said turning meansduring that period of operation lwherein said metering means is axiallystationary at a correlated one of its positions, said operator retainingmeans comprising, longitudinal posts on diametrically opposite sides ofsaid metering means and coextending therewith, said operator havingdiametrically spaced means slidably overlapping said post means forpreventing turning of said operator about the axis of said meteringmeans, axially spaced stop means defining intermediate post portions,forward and rear resilient means operatively associated with each post,the forward resilient means of each post forming a pair being loaded incompression by reason of said operator engaging same as said operatorapproaches a correlated one of its positions until the moving operatoris stopped by the loaded resilient means, the rear resilient means ofeach post forming a pair being loaded in compression by reason of saidoperator engaging same as said operator approaches its other positionuntil the moving operator is stopped by the loaded resilient means,displacement of said operator along said metering means away from acorrelated one of its positions releases the correlated pair of loadedresilient means, wherein said operator traverses the intermediate postportions and then advances to engage the other pair of resilient meansto cause loaded compression thereof until halted, whereby the turningmetering means is axially shifted in the direction. from which saidoperator originated to cause said metering means to disengage acorrelated one of said turning means and engage the other turning means,whereby rotation of said metering I0 means is reversed to effect returndisplacement of said operator;

6. A reversing mechanism for converting contlnuous rotation of a driveshaft in a preselected single direction about its axis into drivenrotation of a second shaft alternately in opposite directions about itsaxis comprising, a drive shaft adapted for turning in a preselecteddirection about its axis, first and second axially spaced drive gearskeyed to said shaft to turn therewith, a driven shaft adapted forturning in either direction about its axis, first and second axiallyspaced metering gears freely rotatable on said driven shaft, an idlergear continuously in toothed engagement with said first drive gear, saididler gear also being continuously in toothed engagement with said firstmetering gear, said second drive gear lbeing continuously in toothedengagement with said second metering gear, -wherein rotation of saiddrive shaft results in continuous rotation of said metering gearsindividually in `opposite directions about the laxis of said drivenshaft, a metering screw adapted for slidable axial displacement alongsaid driven shaft alternately from one to another of two axially spacedlimit positions between said metering gears, means keyed to said screwto shift axially therewith and also to rotate therewith, said keyedmeans axially overlapping the ends of said metering screw to engage eachof said metering gears individually depending whether said screw is inone or the other of its two limit positions, said screw being rotatablyIabout its own axis in the same direction as the engaged one of saidmetering gears, disc means keyed to said driven shaft to rotatetherewith, said keyed means slidably extending through said disc meansto impart rotation to said driven shaft about its axis in the samedirection as imparted to said screw, said screw having a threaded outersurface, a metering nut having an interior thread and being operativelymounted on said threaded outer surface, said nut being adapted for axialdisplacement alternately from one to another Iof two axially spacedlimit positions along said screw, means continuously holding said nutagainst rotation, said screw being adapted to undergo axial displacementalong said driven shaft in alternate directions from one to the other ofits limit positions in response to said nut being restrained in arespective one of its limit positions, means temporarily restrainingsaid nut against axial travel during axial travel of said screw from oneto the other of its limit positions, said restraining means beingadapted to release said nut for axial travel from one to the other ofits limit positions by reason of a correlated rotation of said screw inresponse to said keyed means engaging a correlated one of said meteringgears during that time said screw is held against axial displacement,and said screw being released for axial displacement `along said drivenshaft in response to said nut being retained in iixed relationship at acorrelated one of its limit positions, whereby said keyed means isreleased from engagement with one metering gear and enters intoengagement with the other metering gear wherein rotation of said drivenshaft is reversed.

References Cited in the tile of this patent UNITED STATES PATENTS1,146,228 Zint July 13, 1915 2,801,806 Taylor Aug. 6, 1957 FOREIGNPATENTS 66,725 Sweden May 18, 1927

